Turbocompressor



June 8, 1943. v. 5. DE BOLT TURBO-COMPRESSOR File d Sept. 20, 1939 4 Sheets-Sheet 1 lNV ENTOR June 8, 1943.

V. 8. DE BOLT TURBO-COMPRESSOR Filed Sept. 20, 1939 4 Sheets-Sheet 2 June 8, 1943. -v. 5. DE BOLT TURBO-COMPRESSOR Filed Sept. 20, 1939 4 Sheets-Sheet 3 INVENTOR.

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' TURBO-COMPRESSOR Filed Sept. 20, 1939 4 Sheets-Sheet 4 Patented June 8, 1943 UNITED STATES PATENT OFFICE 2,321,276 'runnocolurnnsson Vaughn S. De Bolt, Washington Court House, Ohio Application September 20, 1939, Serial No. 295,772

Claims.

This invention relates to a turbocompressor, turbopump, turbosupercharger, turbotransmisrsion.- exhaust driven supercharger, gas turbine, and the like. where an impeller energizes a fluid producing pressure energy and velocity energy which velocity energy is then changed into pressure energy.

The turbopumping devices of hitherto knowndesign produce a pressure by means of centrifugal force; however, there is usually about 50% of impeller energy transformed into velocity energy of the whirling fluid which energy must be changed into pressure by diverging vanes, by a diilusor or a. guide wheel, by a whirlpool chamber, volute or spiral housing. As well known, this change of velocity into pressure is very inefilpeller and its diflusor, whereas large part of velocity energy is absorbed by turbine blades very emciently and does not need to be changed into pressure energy. In this way I can reach eillciency of 95%; this represents a great saving which is the main object of the invention.

Another object of the invention is to gear the mentioned turbine to the pump in such away that all energy absorbed by the turbine helps to drive the pump.

Another object of the invention is to change this gearing, to lock the turbine or to unlock it and let to run free in order to change characteristics of the pump.

Another object of this invention is to make possible to design extremely high speed pumps and still keep their efliciency high because of comparatively low entrance velocity into guide vanes because the guide vanes (turbine) move in the direction of fluid flow.

'This invention is applicable to pumps, compressors, superchargers, turbo transmissions, and the like, increasing their efllciencies.

Other objects of the invention are: simplicity, compactness, low manufacturing cost, and above all increase in efficiency heretofore not obtainable.

With these and other objects in View my invention consists in the combination, arrangement and construction hereinafter described, claimed and illustrated in the accompanying drawings, it

being understood that many changes may be made in size, proportion of the part and details of construction within the scope of the appended claims, without departing irom the spirit or sacriflcing advantages or the invention.

Some or the many possible embodiments of the invention are illustrated in the accompanying drawings.

Figure 1 is a diagrammatic section taken on line l- --l of Figure 2 illustrating a turbo pump constructed in accordance with my invention.

Figure 2 is a diagrammatic longitudinal section of the pump of Figure 1.

Figure 3 is a longitudinal section of an alternative design of a pump.

Figures 4 and 5 illustrate diagrammatically a radial multistage turbo pump.

Figure 6 is a longitudinal section through a semi radial compressor.

Figure 7 illustrates blading of an axial multistage compressor.

Figures 8 and 9 are longitudinal sections showing single stage superchargers.

Figure 10 illustrates blading of the superchargers of Figures 8 and 9.

Figure 11 is a halt longitudinal'section through a two stage turbocompressor.

Figures 12 and 13 illustrate velocity diagrams of a turbopump.

Figure 14 is a half longitudinal section showing a. multistage supercharger with its transmission constructed in accordance with my invention.

Fig. 14A illustrates diagrammatically a valve mechanism of Fig.14.

Figure 15 shows a vertical supercharger.

Figure 16 is a longitudinal section showing a turbine driven supercharger.

Figure 17 shows a nozzle of the same super charger.

Figure 18 is a section illustrating a double suction pump.

Figure 19 is a longitudinal-section showing a two stage turbocompressor.

Figure 20 illustrates diagrammatically a pump having a whirlpool chamber and a spiral case.

Figure 21 shows a pump with difl'usor ring and spiral case.

Figure 22 illustrates turbine blades.

Fig. 22A illustrates an alternative design of the blades of Fig. 22.

Centrifugal pumps of today for compressible or I non compressible fluids consist mainly of impeller surrounded by a. diilfusor containing difiusion vanes which provide gradually. enlarging passages whose function it is to reduce velocity of the fluid leaving the impeller and thus trans form velocity head into pressure head. The casing surrounding the diffusion ring may be either ference and also to gradually reduce the velocity of the fluid as it flows from the impeller to the discharge pipe. Thus the energy transformation is accomplished in another way. The spiral is often called a volute whence the pump has received its name: a volute pump.' Occasionally pumps have been built with what is called a whirlpool chamber. This consists of a ring surrounding the impeller, the width of which, parallel to the shaft, is the same as that of the impeller. Since the fluid from the impeller enters this space with a velocity having a tangential component it may be seen that the path of the fluid will be some form of a spiral and that its velocity will gradually diminish as it approaches the outer circumference with a consequent increase in pressure. This whirlpool chamber is then surrounded by either a circular or a spiral case in the same manner as a pump with a diflusor. Actual measurements indicate that the efficiency of diflusors, volutes, whirlpool chambers or spiral cases is poor, it very seldom reaches 50%, because the change of kinetic energy into potential energy is not complete nor gradual, especially at high speeds.

Pumps designed according to this invention differ from the pumps as known today by having a rotary turbine runner at the periphery of impeller inserted between exit from the impeller and the entrance into the diflusor or volute.

The turbine blades rotate usually slower than the impeller and absorb large part or all of the kinetic energy from the fluid. This energy can be either brought back to the impeller or can be used for some other purpose such as driving accessories on airplanes, automobiles, boats, which are not shown here, etc.

Figures 1 and 2 illustrate a pump having an impeller 38 with blades 58 and turbine 92 with radial antireaction blades I08 rotating in the housing I56; the impeller being mounted on a shaft is driven by a belt pulley I54; the-turbine being integral with a sleeve I51 drives a belt pulley I55. These pulleys are driven by another common pulley I63 by means of belts I8I and I62 or they can be driven by different pulleys by means of an electric motor, engine or turbine (not shown). Turbine is equipped with thrust geared together by means of a countershaft Ill being integral with gears I65 (in mesh with gear I64) and I66 meshing with gear I81. The turbine 94 is provided with balancing openings 352 and has blades III) and II I. The impeller has blades 58 and 59.

Long arrows indicate high speeds of impellers, short arrows represent medium speeds of turbines.

The impeller and the turbine are, of course, to

be inserted in a casing with a stationary diffusor or volute or spiral chamber (not shown).

Figure 6 illustrates'an embodiment of the invention what can be called a semi axial flow compressor.

An impeller H and a turbine 95 rotate in a casing I10 equipped with a diffusor I38. For a peller under positive pressure which insures betbalancing openings 350. Long, solid line arrow indicates high rotary speed of impeller; short solid line arrow indicates medium rotary speed of turbine; dotted line arrows indicate relative velocity of fluid through blades (similar designation being used throughout entire specification).

In Figure 3 somewhat different arrangement is used:

A belt pulley I59 drives an impeller 39 by means of a sleeve I60; a turbine 93 mounted on a shaft 26 drives a pulley I58. The impeller 39 carries blades 51 and is provided by balancing openings 35I; the turbine 95 has blades I89.

Figures 4 and 5 illustrate a two stage radial pump having an impeller 40 driven by a shaft 21 which is equipped with a gear I61, and a turbine 94 driving a gear I64; gears I61 and I64 are then V by backward turned blades ter volumetric and overall efl'lciency.

Figure 7 illustrates a two stage blading of a compressor otherwise similar to the pump of Figure 6. Here slow speed impeller vanes I14 feed fluid into high speed impeller blades 6I and further 62. Turbine blades I I3 and H4 drive the entrance impeller blades I14 in a similar way as in Figure 6.

Figures 8, l0, l2 and 13 illustrate a supercharger for aircraft engine: driving gears I16 and I 11 rigidly fastened together mesh with gears I18 on impeller shaft 29, and I19 driven by a turbine 96 equipped with blades II5 preferably riveted to the turbine or fastened in any other way well known in turbine practice.

Entrance impeller blade ring held to a driving shaft 29 and to an impeller 42 having vanes 63 by a nut I83 suck the air into main impeller blades 63; these blades must be of straight radial design because of high rotative speeds used in superchargers (30,000 R. P. M. and more) in order to withstand stresses due to centrifugal force. At the exit from the blades 63 arevdischarge impeller blades 84 turned backwards (see Figures 10 and 13) to diminish the percentage of kinetic energy of fluid.

In diagram of Figure 13: u=peripheral velocity of the blades 84, v=abso1ute velocity of air from the blades 84, w=relative velocity between the blades, c=discharge angle of blades; 1) (dotted) =absolute velocity of air if radial blades were used c=), w (dotted) =corresponding relative velocity. The diagram plainly shows how the absolute velocity V' was diminished to V The blades 84 must be of substantially axial or semiaxial type and fastened by dovetailing to a disc I82 or otherwise as known in high speed turbine practice (especially De Laval) so they couldwithstand stresses due to centrifugal forces. In order to obtain full benefit of this reduction of absolute velocity and resulting decrease of kinetic energy of fluid by exit blades 84 suflicient guidance of the fluid must be provided. This is accomplished by proper ratio of pitch of vanes to depth or axial height of blades. Fig. 10 illustrates blades 84 having depth of blades or axial height of blades )2 about equal to circumferential pitch 1: of blades or, about eqi'ial to radius r of, the curvature of the blades. Similar rule must apply to blades 13 if the losses due to improper guidance are to be avoided. In thecase of turbine blades I I5, deviation angle of the fluid due to blades I I5 being greater, necessary depth or axial height H of blades must be slightly greater than circumferential pitch P of the turbine blades, as can be readily seen in Fig. 10; this again to provide suflicient guidance in order to deflect the fluid properly, without losses due to turbulence, etc. The turbine is provided by balancing openings 354 and labyrinth seal 310.

In diagram of Figure 12 illustrating function of the turbine blades IIB: U=peripheral velocity of blades I I5, Wi=inlet relative velocity, V1=absolute inlet velocity which equals to velocity v of diagram Figure 13; Wo=outlet relative velocity, V=absolute outlet velocity. The velocity V is transformed into pressure by difiusor blades I32 secured to a housing I34 having a bearing I80 to support a hub I85 integral with gear I19, to which hub turbine 36 is fastened.

It is obvious that no stationary diffusor is necessary when all kinetic energy of fluid is absorbed by turbine.

Figure 9 shows a similar aircraft supercharger as shown in Figure 8 and functioning in a similar way, the only difference being in drive:

A central shaft I99 driven by a crankshaft of an aircraft engine carries a gear I9I in mesh with a pinion I92 on a countershaft I93; to the countershait are fastened gears I95 and I34 meshin with pinions I and I91; pinion I98 drives an impeller 43 by means of a hollow shaft 30; pinion I91 is driven by a turbine 91 by means of a hollow shaft I98; shaft I90 is supported by a bearing I31 in a supercharger housing I83 equipped with diffusion vanes I33. The impeller 43 has entrance blades 19, main blades 64 and exit blades 85 similar to blades 04. The turbine 31 carries blades II6 similar in design to blades II 5.

In Figur 11 is illustrated construction of a multistage (2 stages shown) aircraft supercharger having two speeds and stop-supercharging (without stopping rotation of the impeller and with out wasteful throttling) and equipped with automatic as well as hand control to operate each speed or stop according to altitude in which the airplane operates, or at will, in fact, there are provided four different operating functions resulting in four different final pressures obtained by this supercharger, as will be shown in description:

A driving-shaft 200 carries gears 202, 205 and 209 meshing with pinions: 203 driven by a hollow turbine shaft 2I5; pinion 206 secured to an impeller driving shaft 3| and finally. pinion 201 which also drives the impeller shaft 3I but by means of one-way clutch 208. To the shaft 3i are secured impellers 44 with blades 55, and 45 with'blades 66. Turbine 98 with blades Ill, and

99 with blades I I8 are mounted rigidly to the hollow shaft 2 I5. Both turbines are secured to a rotary casing 235. Impellers and turbines rotate in a stationary housing 2 having small clearance rings 2I3, 2I4 and a labyrinth packing 2I2. Dotted arrow indicate again path of fluid.

Automatic and hand controlled drive functions as follows:

A hand lever 2I0 pivoted at 2I6 to the housing 2 applies a brake 2I1 against the pinion 203;

whenever the brake is applied turbines stop from rotation and supercharger produces maximal pressure because more energy is put in, no energy being transformed back into mechanical energy by turbines. This compression is obviously not means of a lever 220 pivoted at 22I:

Whenever atmospheric pressure against the piston 228 overcomes the spring 224 and pressure inside the cylinder 222 (the inside of the cylinder being connected to an engine manifold, not shown, or to the outlet end of an exhauster by a pipe 223) a lever 220, pivoted at 22I, disconnects the clutch 20I against pressure of a spring 2I9 with result that gear 202 is free to rotate. When, however, spring 224 plus pressure inside of the cylinder 222 overcomes atmospheric pressure on the right side of the piston 225 the clutch 20I is connected and the gear 202 is put into rotation.

Whenever the turbines are free to rotate no reaction can be created within the supercharger and the result is that the impellers run free, not I absorbing any energy nor creating any pressure, but simply not energizing the fluid because there cannot be any action where there is no reaction.

A cable 221 is provided for hand operation of I the clutch 20I in emergencies or any time at will. In a similar way a cylinder 229 with spring 230 operates a piston 23I and a connecting rod 232 by means of a lever 231 pivoted at 233.

It is expressly to be understood that springs 224 g and 230 can be either compression or tension springs, as required.

Whenever atmospheric pressure on the right side of the piston 23I overcomes the spring 230 and pressure inside the cylinder 229 (the cylinder being connected to the engine manifold or to the outlet end of an exhauster) piston 23I and connecting rod 232 move to the left turning a lever 231 against a spring 234, thus disconnecting the clutch 204 and making the gear 205 run free. Whenever the gear 205 is free, power is trans mittedlfrom the shaft 200 tothe shaft 3I by means of gear 209 to a pinion 201, then by a oneway clutch 208 to the shaft 3I; this is the low speed of the impellers resulting in the low pressure of the supercharger.

When, however, the atmospheric pressure is low, piston 23I moves to the right and lever 231 connects the clutch 204 by means of spring 234. Whenever clutch 204 is connected, power is transmitted directly from the shaft 200 to the shaft 3I by means of gear 205 and pinion 206 (while pinion 201 rotates freely on its one-way clutch). This is the high speed of supercharger, resulting in high pressure rise in the manifold or in cabin.

and impellers rotate at high speed, resulting in high pressure rise.

At extremely high altitudes or in emergency (as on combat or stratosphere planes) turbines are stopped by brakes while impellers run at high speeds which results in maximal pressure rise.

The advantage of this construction against those hitherto known is obvious: without wasteful throttling I obtain four different increases of pressure necessary for different altitudes.

Figure 14 illustrates another multistage turbocompressor for supercharging aircraft engines with automatic altitude control.

A central shaft 248 supported by a hollow impeller shaft 32 and by bearings 268 and 281 supported by stationarycompressor case 284 and transmission case 253 and driven by a crankshaft (not shown) drives a gear 2 in mesh with pinion 242 which is integral with gears 243 and 244. These gears are mounted freely on a countershaft 258' supported by bearings 25I and 252. Gear 243 drives a pinion 246 while gear 244 drives a pinion 241 and then one-way clutch 248.

Pinion 246 being integral with outer clutch part 388 drives a disc "I whenever the wedges 382 are forced from the center by means of rollers 384 and conical surface 386 of a sliding sleeve 885. By means of this clutch pinion 246 drives a hollow shaft 32 supported by bearings 281 and 381 which shaft in turn rotates impellers 46 and 41. The impellers are provided by entrance blades 88 and 8| and by axial exit blades 86 and 81, preferably dovetailed to impellers. The numerals 295, 312, 313 indicate labyrinth seals; numerals 358, 353, 368, and 36I indicate fluid pressure balancing holes; numerals 29I, 292, 293 represent seal or packing rings. The numerals 388-384 represent small clearance rings to prevent short circuiting of the fluid.

Second stage turbine diffusor blades H9 are secured to a, rotary flange I88 on one side and to a rotary housing 28I on the other side; the flange I88 is supported by a bearing 281 secured to the hollow impeller shaft 32. Housing 286 is fastened to'a first stage rotary housing 285 which in turn is carried by a rotary flange 284 fastened to a sleeve 282 equipped by a difiusor gear 248 and supported by a bearing 283 which in turn is secured in the transmission case 253.

First stage turbine difiusor blades I28 are secured between the housing 286 and a shroud "I and ar of a similar design as the blades illustrated in Figures 1, 10, 22, or 22A. The gear 245 is in mesh with the turbine difiusor gear 249; the gear 245 is either:

(A) Coupled by the clutch 255, or,

(B) Free to rotate on the shaft 258, or

(C) Stopped from rotation by a brake 215 for emergency purposes. I

Shaft 258 carries freely a gear 245 and a sliding friction clutch 254 with a spring 255; a lever 251 pivoted at 256 and operated by a connecting rod 258 and piston 258,locks and unlocks the clutch according to which side of piston the oil pressure (or any other fluid under pressure) is admitted in a cylinder26l through a pipe 262 or a pipe 263. A valve 265 regulated by a lever v266, connecting rod 261, diaphragm 268 and spring 218; a pipe 268 connects the inside of the diaphragm with a manifold (not shown) or with the exit from the supercharger.

In Figure 14A is shown the outlet for the oil from the cylinder 26I; a valve 2 connected to the valve 265 and operated by the same lever 266 connects the cylinder 26l either with a pipe 213 or a pipe 214 and drains one side of the piston 258 so the oil on the other side of the piston could move the piston toward the side being drained.

Whenever the pressure in manifold or in outlet from supercharger increases the diaphragm 268 expands pushing lever 266 to the left which opens pipe 263 to pressure oil coming from pipe 264; at the same time lever 266 turns the valve 21I so the pipe 214 could drain the right side of cylinder 26I, which results in piston 258 moving .to the right. The piston pulls rod 256 and disconnects the clutch 254 against pressure of a spring 255. Turbines having blades H8, I26 of substantially similar diverging or antireaction" design as illustrated in Figures 1, 10, 22 and 22A are then free to rotate, as there is no or. very little reaction there can be no or very little action and therefore supercharger produces no or very little pressure.

Similar control (not shown) by manifold pressure and oil pressure is intended for control of clutch 38I which results in:

(a) Transmitting power to impellers by large pinion 241 and one-way clutch 246 which is a low speed drive, main clutch 38I being disconnected, or

b) Transmitting power to impellers by a small pinion 246 and through clutch 38l which is a high speed drive.

For emergency purposes when maximal air pressures are needed there is a brake 215 provided, which stops gear 245 and thus the turbines from rotation which in turn produces maximal air pressures. The brake is operated at will by a lever 218 pivoted at 219.

Thus I have provided in this embodiment:

(a) No or very small increase of air pressure for sea level because turbines are free to rotate;

(b) Small pressure increase for moderate altitudes when turbines operate normally and impellers rotate at low speed;

(0) High pressure increase for high altitudes when turbines operate normally and impellers rotate at high speeds;

(d) Maximal air pressure for emergency or special purposes when turbines are stopped and impellers rotate at high speed.

Figure 15 illustrates a vertical supercharger where friction roller drive is used to increase speed of impellers. A driving shaft 3I8 supported in a supercharger housing 3 I 6 drives a roller cage 3| I with larger rollers 3 I 2 and smaller rollers 3 I3; rollers 3I2 support and operate impeller shaft 33 with impeller 44, with main blades 68, outlet impeller blades 88, which impeller is fastened to its shaft by taper fitting and a nut 3I1, while smaller rollers 3I3 support and rotate a turbine hub 3I5 integral with turbine I82 equipped with blades I2I. Both, smaller and larger rollers rotate in a stationary sleeve 3I4 pressed in the housing 3I6. Due to the size of rollers the hub 3I5 rotates slower than the shaft 33.

It is obvious that gears could be used instead of rollers; in that case sleeve 3| 4, shaft 33 and hub 3I5 would have gear teeth to mesh. Numeral I36 represents a diflusor, numeral 362 indicates a balancing hole.

Figures 16 and 7 illustrate a gas or steam turbine driven supercharger. Gas or steam coming out from a stationary nozzle 328 enters into rotating nozzles 32I and then into main turbine or driving blades 322 which blades are carried by a disc 324 mounted to the shaft 34 which carries also an impeller 58 withimpeller blades :2 this shaft is supported by bearings 326 and Nozzles 32I carried by a disc 323 are mounted on a hollow shaft 325 which is supported in a housing 328 and carries on its other end a pumping turbine I03 with blades I22; stationary diflfusion blades I01 are provided in the housing 020.

The advantage of rotary nozzles "I is shown in Figure 17: nozzles rotating in the direction of turbine rotation can have larger discharge angles C than stationary nozzles shown in dotted lines with discharge angle because rotating velocity adds to the peripheral velocity of gas.

Figure 18 illustrates a double turbocompressor to balance axial thrust. A main driving shaft 35 supported by bearings 333 and 334 in a housing 332 drives impellers and 52 with blades II and I2. At the periphery of impellers there are turbine blades I23 and I24 of a turbine I04; this turbine being supported by bearings 535 and 3 35 drives inlet impeller 330 on one side and 03I on the other side, forcing the air into the main impeller blades II and 12. In this way it is not necessary to gear the turbine to the impeller orto the driving shaft because the energy absorbed by the turbine is used by entrance impellers and does not need to be returned. Numerals I38, I42 represent difiusors, numerals 355, 356 indicate balancing holes.

Figure 19 shows another embodiment of the invention suitable for highest speeds where turbine energy is used up directly in compressing the fluid so the turbine does not need to be geared to the impeller or to the driving shaft.

A driving shaft 36 supported by bearings 340 and 3 drives an impeller 53 having entrance blades 82, main blades I3 and, outlet blades 89 dovetailed into impeller. On the same shaft is mounted free to rotate a turbine I05 with blades I25; the turbine is integral with a secondary impeller 54 having entrance blades 83, main blades 14 and outlet blades 90. The main impeller, turbine and secondary impeller rotate in a stationary housing 342 having a difiusor I39 and difiusor I40 and said bearings 340 and.34I. Numerals 351, 368 represent balancing openings, numerals 315, 316 indicate labyrinth seals.

All kinetic energy absorbed by the turbine I05 is transmitted to the secondary impeller where again pressure and velocity head is produced. However, the speed of this secondary impeller is only about half the speed of the main impeller; thus the losses in kinetic energy are much smaller.

Figure 21 represents a typical design of a centrifugal pump constructed according to the invention.

The pump in Figure 21 consists of an impeller 16 and rotary difiusor I21 (or turbine), rotating within a case I53 and a stationary difiusor or guide wheel fastened to the case. Fluid enters the impeller at the center, flows radially outward, is discharged from the impeller into the turbine I21, into a stationary difiusor I and finally into a spiral case I53. During this flow thru the impeller the fluid has received its energy from the vanes 'Il resulting in an increase both, in pressure (potential energy) and velocity (kinetic energy). Since the large part of the energy of the fluid at discharge from the impeller is kinetic (about 50% with radial vanes) it is necessary to transform it or, at least greater part of it, into mechanical energy by a substantially impulse ggurbine I21 since it is impossible by present day 'methods to transform it into pressure very efliciently by diverging diffuser vanes.

The turbine blades rotating at about half of the impeller speed or a little faster are preferably not entirely impulse blades but somewhat diverging blades (antireaction) as shown in Figure The kinetic energy absorbed from fluid bythe turbine can be either brought back to the impeller shaft by proper gearing or belting, or can be used for some other purpose such as driving accessories on airplanes which are not shown here, etc.

The pump illustrated in Figure 20 differs from the pump inFigure 21 only by having avolut'e" chamber I5 I instead of a' stationarydiflusor. Numeral I6 indicates impeller blades, I10 represents turbine blades, I52 is a spiral case.

All other pumps or compressors function-in a a similar way as described in the case of Figure 21.

Figure 22 illustrates turbine antireaction blades I28 having entrance angle B smaller than discharge angle C. Figure 22A shows turbine blades IZBA of streamline shape with thick and round entrance edges for variable angle B. Turbine blades used in the embodiments of the invention can be called: diffuser blades absorbingenem or, turbine diffusor blades" or rotaryjdiffusor or antireaotion blade wheel.

Basically the invention is a pumping device energizing a fluid, whereas part of the fluid energy is transformed back into mechanical energy by a substantially rotary difiusor.

The invention represents a new methodof pumping a fluid by producing potential and kinetic energy in the fluid and then absorbing part of one of the energies from the fluid by a substantially rotary difiusor.

The invention is basically a pump energizing a fluid, whereas part of the fluid energy is transformed back into mechanical energy in order to assist in driving the pump.

I claim:

1. A fluid compressor comprising an outlet for the fluid, an impeller producing potential and kinetic energy in the fluid and forcing the fluid thru the outlet out of the. compressor, a rotary 'diifusor absorbing the kinetic energy from the fluid, an operative connection between the impeller and the diffusor to transmit the absorbed energy from the diifusor to the impeller, means to disengage said connection, and means to stop the rotary diflusor from rotation so as to increase the fluid pressure at the outlet.

2. In a combination, a fluid compressor com"- prising an impeller producing potential and kinetic energy in the fluid to be compressed, a turbine absorbing the kinetic energy from the fluid, and a gas, steam or exhaust turbine driving said compressor, and comprising rotary nozzles and a turbine runner, said impeller driven by said turbine runner, said rotary nozzles duce amount of the kinetic energy, circumferential spacing or pitch p of the exit blades beingabout equal or smaller than the axial height h or depth of the,blades, or, mathematically: ph,

and a turbine absorbing part or the energy from the fluid.

4. A fluid compressor comprising a casing and an impeller in the casing producing potential and kinetic energy in the fluid, the impeller having main radial blades and substantially axial exit blades, said exit blades being curved backwards to reduce amount of the kinetic energy, circumferential spacing or pitch 9 or the exit blades being about equal to radius of curvature oi theexit blades or, mathematically expressed: p=r, and a turbine absorbing part of the energy from the fluid.

V. 8. DE BOLT. 

